Technically 'leading from the front' is somewhat of a misnomer. While many of the officer corp did advance to the front during battle in order to encourage their troops to greater valor or effort their actual position in a battle formation was SUPPOSED to be behind the battle line where they could observe the formation and the eb and flow of the changing situation and recieve orders from their higher commander.

While in parade formation and even advances across open ground the senior officers did 'lead' while in front of their formations. But once these formation got within "rifle range" (about 400 yards) they were supposed to assume their position behind the lines. Only the Captains of companies would remain in his position on the front rank of the Battle line while it continued to advance, acting as a guide to keep his company in alinement with the rest of the companies of the regiment, after that point.

The actual "Guides" in the final assualt phase were supposed to be the 5th Sargeants of each company, who were supposed to be (I believe) 25 paces ahead and in front of the captains of their respective company to keep them directed towards the enemy and their objective.

At the point where the regiment reached it 'firing line position' or at the point where the charge was ordered, the Captain (and 5th Sargeants) would withdraw to his (their) position in the rear and be replaced by the 1st Sargeant until the Company actually began shooting at which point even the 1st and 2nd Sargeant would step back 5 paces to become markers for the Captain to know where his comapny was in the smoke and confusion.

So in the final phase of the Battle the only Officers or NCO's who were actually supposed to be "up front" were the 1st, 2nd, 3rd and 4th Corporals, as they controlled the alinement of the front ranks of each platoon.

Now was this always followed? NO. It was much too complicated to always fully accomplish during the heat and confusion of battle. The Officers always felt the need to personally intervene in the conduct of the battle.

Were the Officers "out of danger' because they were behind their battle lines? Certainly not. We are in fact only about a distance of 5 to 10 yards for the company level officers at best and usually less than that because of the noise of battle.

Regimental Grade Field officers (Colonels, Lt. Colonels, and Majors) would have been located not far behind the Company officer. The Lt. Colonel and Major acting as right and left wing commanders of the regiment (each exercising command over 5 companies) while the Colonel commanded the whole regiment.

A Brig. General commanding 4 to 6 regiments would have normally been behind these Colonels. A Major General commanding a Division would have been located behind the Brig. Generals that he commanded. These men were expected to be where they could be found usually behind the middle of their commands where they could be sent orders from the Corp commander and army commander.

Again This is all textbook depending on which textbook you read.

SO in answer to the original question, These officers were NEVER expected "OFFICIALLY" to 'Lead from the Front'. Yes, Leadership was expected, Courage in the face of danger in battle was also expected, but foolhard exposure to the dangers of the battllefield was not expected as a matter of course. After all, how can a general give a commander orders if he can not be reached because he is in front of his troops, or he is dead? And as was demonstrated all during the War, that good men were hard to replace. Just think of Stonewall Jackson had he not been mistakenly shot and his talents lost after Chancellorsville, because he foolishly exposed himself "scouting" the frontline positions in the dark.